jffs2: Require jffs2_garbage_collect_trigger() to be called with lock held

We're about to call this from a bunch of places which already hold
c->erase_completion_lock, so add an assertion and change its existing
callers to do the same.
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

fs/jffs2/background.c

@@ -23,10 +23,9 @@ static int jffs2_garbage_collect_thread(void *);
 
 void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c)
 {
-	spin_lock(&c->erase_completion_lock);
+	assert_spin_locked(&c->erase_completion_lock);
 	if (c->gc_task && jffs2_thread_should_wake(c))
 		send_sig(SIGHUP, c->gc_task, 1);
-	spin_unlock(&c->erase_completion_lock);
 }
 
 /* This must only ever be called when no GC thread is currently running */

fs/jffs2/nodemgmt.c

@@ -481,7 +481,9 @@ struct jffs2_raw_node_ref *jffs2_add_physical_node_ref(struct jffs2_sb_info *c,
 void jffs2_complete_reservation(struct jffs2_sb_info *c)
 {
 	D1(printk(KERN_DEBUG "jffs2_complete_reservation()\n"));
+	spin_lock(&c->erase_completion_lock);
 	jffs2_garbage_collect_trigger(c);
+	spin_unlock(&c->erase_completion_lock);
 	mutex_unlock(&c->alloc_sem);
 }
 

fs/jffs2/super.c

@@ -63,7 +63,9 @@ static void jffs2_write_super(struct super_block *sb)
 
 	if (!(sb->s_flags & MS_RDONLY)) {
 		D1(printk(KERN_DEBUG "jffs2_write_super()\n"));
+		spin_lock(&c->erase_completion_lock);
 		jffs2_garbage_collect_trigger(c);
+		spin_unlock(&c->erase_completion_lock);
 		jffs2_erase_pending_blocks(c, 0);
 		jffs2_flush_wbuf_gc(c, 0);
 	}